(Capcom's primary storyline)
Bronson was one of the field agents of the Private Anti-Biohazard Service who was sent to the Russia mission. He died during the mission and his corpse was found by Chris Redfield and Jill Valentine.
The death of Bronson left Chris grieved, but Jill quikly motivated him to go on by remembering about their mission and that should they fail, Bronson's death would have been for nothing. They then could gather ammunition from his remains.